Patent GB-905070-A (GB)
Title: Improvements in the production of photopolymerisable compositions containing cellulose esters
IPC: G03F7/032
Filed: 1960-08-26
Abstract: An addition photopolymerizable composition is made by admixing finely divided particles, capable of passing through a screen having uniform openings not greater than 0,027 inch in their largest dimension, of a cellulose partial ester of at least one saturated aliphatic monocarboxylic acid having 2-4 carbon atoms, with a dicarboxylic acid anhydride and a non-gaseous addition-polymerizable ethylenically unsaturated compound, heating the mixture while mixing at from 80 DEG -185 DEG C., admixing an esterification catalyst and maintaining the resulting composition at between 80 DEG -185 DEG C. until esterification is substantially complete.  In a modification, the dicarboxylic acid anhydride may be partly or wholly replaced by a monocarboxylic acid anhydride. Preferably the cellulose ester is a cellulose acetate with a degree of substitution of 1,8-1,9, but cellulose acetatepropionate, cellulose acetate butyrate, cellulose propionate and cellulose butyrate, having some free hydroxy groups, may be used.  The cellulose ester particles may have their greatest dimension in the range 0,006-0,027 inch.  The preferred dicarboxylic acid anhydride is succinic anhydride, but others specified include glutaric, maleic, phthalic, tetrahydrophthalic, and hexahydrophthalic, and endo-cis-Bicyclo-[2.2.1]-5-heptene-2,3-dicarboxylic anhydride. Preferred monocarboxylic acid anhydrides are those with 2-18 carbon atoms, especially 2-4 carbon atoms; propionic anhydride is specified. The composition of the cellulose partial ester and the amount of dicarboxylic acid anhydride used should together correspond to a degree of substitution by the monocarboxylic acid of 1,8-1,9 and by the dicarboxylic acid of 0,6-0,9 carboxyl groups per glucose unit. The ethylenically unsaturated compound is preferably an acrylic acid diester of ethylene glycol or of a polyethylene glycol having an average molecular weight less than 600.  Those specified include triethylene glycol diacrylate which is preferred, ethylene glycol diacrylate, diethylene glycol diacrylate, tetramethylene glycol diacrylate, diallyl itaconate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and tetramethylene glycol dimethacrylate. As esterification catalyst a tertiary amine may be used, e.g. diethylcyclohexylamine, pyridine, triethylamine, tributylamine, triamylamine, trimethylamine acetate and pyridine acetate, or an inorganic catalyst, e.g. sodium carbonate, borate and phosphate, sodium, lithium, calcium, potassium and magnesium acetates, and potassium carbonate.  An addition polymerization initiator activatable by actinic light and inactive thermally below 80 DEG C., preferably below 185 DEG C., may be incorporated in the composition. Examples include 9,10-anthraquinone, 1-chloroanthraquinone, 2-chloroanthraquinone, 2-methylanthraquinone, 2-t-butylanthraquinone, octamethylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthrenequinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-methyl-1,4-naphthoquinone, 2,3-dichlornaphthoquinone, 1,4-dimethylanthraquinone, 2,3-dimethylanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, the sodium salt of anthraquinone a -sulphonic acid, 3-chloro-2-methylanthraquinone, retenequinone, 7,8,9,10-tetrahydronaphthacenequinone, and 1,2,3,4-tetrahydrobenz[a ]anthracene-7,12-dione.  The mixture may also contain 0,5-9%, based on the weight of the composition, of p  a calcium salt, especially calcium acetate (calculated as anhydrous), chloride or nitrate which should be present during the esterification, a saturated plasticizer, e.g. triacetin, glyceryl tributyrate, triethylene glycol dipropionate, triphenyl phosphate and dimethyl phthalate, and 0,001-2% by weight based on the ethylenically unsaturated compound, of a thermal polymerization inhibitor, e.g. p-methoxyphenol, hydroquinone, alkyl and aryl-substituted hydroquinones, t-butyl catechol, pyrogallol, naphthylamines, b -naphthol, p-benzoquinone, 2,6-di-t-butyl-p-cresol, dicyclopentadienyl iron, phenothiazine, pyridine, nitrobenzene and dinitrobenzene, p-toluquinone, chloranil, and thiazine dyes, e.g. thionine, thionine blue G, methylene blue B and toluidine blue O.  Preferably, each of the heating steps is carried out for a period of 5-30 mins.  In a preferred method, a mixture of finely ground cellulose ester, ethylenically unsaturated monomer, dicarboxylic acid anhydride and preferably an addition polymerization initiator and thermal polymerization inhibitor is mixed at 80 DEG -180 DEG C. for about 5-20 mins., allowed to cool, and ground into fine particles, which are then moistened with esterification catalyst, and the esterification completed without further mixing by heating at 80 DEG C. for 4 hours.  A layer of a composition made according to the invention may be pressed to form a photopolymerizable sheet.  (For details of the application of the invention to the construction of photographic elements, see Group XX).  Specifications 741,294, 741,441, 741,570, 771,148, 843,238, 864,041 and 883,558 are referred to.